PROJECT SUMMARY/ABSTRACT The burden of prostate cancer in the U.S. is large: an estimated 14% of men will be diagnosed with prostate cancer during their lifetime. There are approximately three million prostate cancer survivors in the U.S., and the burden is highest among black men, for whom incidence and mortality rates are 169.4 and 69.0 per 100,000, respectively. The introduction of prostate-specific antigen screening has resulted in detection of more cases of prostate cancer, although many of these cases are asymptomatic and may not progress to clinical significance. Active surveillance is a management option for low-risk prostate cancer patients, during which the disease is actively monitored. Active surveillance patients are an ideal population for lifestyle interventions, which may improve diet and physical activity, reduce body mass index, and improve clinical biomarkers, thus reducing risk of other chronic conditions and second primary cancers and improving patients' quality of life. Thus far, several lifestyle interventions for patients undergoing active surveillance have had positive results; however, none have targeted spouses or partners, or black men, in their design and implementation. The proposed study seeks to pilot test Watchful Living, an innovative, culturally-relevant social support lifestyle intervention during active surveillance for black prostate cancer patients and their partners. Our specific aims are: 1) To determine the feasibility of recruiting and implementing a lifestyle intervention during active surveillance for prostate cancer patients and their partners, 2) To evaluate preliminary efficacy of an active surveillance lifestyle intervention in improving diet, physical activity, quality of life, and inflammation at the end of the study (Month 6), and 3) To conduct a process evaluation of the active surveillance lifestyle intervention. We will recruit 40 patient-partner dyads from MD Anderson Cancer Center and Lyndon B. Johnson Hospital, who will receive dyadic telephone coaching, exercise prescriptions in a home-based physical activity program, nutrition counseling with a registered dietitian, and educational handouts. Watchful Living has the potential to ultimately prevent morbidity and mortality due to prostate cancer by significantly reducing chronic diseases and second primary cancers, and improving the quality of life of black patients and their partners. Pilot funding is critical to demonstrating the feasibility and preliminary efficacy of our intervention. With this pilot data, we will apply for an R01 to adapt, implement, and evaluate the intervention on a larger scale.